When I tried to read nextline, the pointer in the while loop reads two lines at a time. Is there another creative way to deal with the file's next line?

use strict;
use warnings;
my %store; my $nextline; my $cnt=1;
my $filename = "$ARGV[0]";
open(my $fh, '<:encoding(UTF-8)', $filename) or die "Could not open fi
+le '$filename' $!";
     
while (my $row = <$fh>) {
    chomp $row;
    my @tmp = split /\s+/, $row;
    $nextline = <$fh>; chomp $nextline;
    my @nexttmp = split /\s+/, $nextline;
print "$row\t$cnt\n";
    if ($tmp[0] ne $nexttmp[0]) { 
        $cnt++; 
    }
print "$nextline\t$cnt\n";

}
close $filename;
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